Metabolically active biological materials (e.g., cells) are phenomenal biochemical catalysts capable of carrying out sequential, stereospecific biochemical reactions. There are significant potential industrial and environmental uses of metabolically active biological materials. They can be used for a variety of purposes such as converting organic waste materials to useful liquid fuels, solvents, gaseous fuels, or to generate electricity in microbial fuel cells. In particular, anaerobes and phototrophic (light trapping) microorganisms that use light to generate cellular energy would be very useful industrial biocatalysts if a method can be found to distribute these living cells uniformly over the surface of electrodes or over a large light-trapping surface area at high cell density.